Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is fully covered. The description adds only the return shape, which is already available in the output schema, and says nothing about per-shape parameter requirements or validation behavior.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two short front-loaded sentences that lead with the action and resource. The 'Returns: {shape, perimeter}' clause duplicates the output schema, which is mildly wasteful, but nothing else is padded.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

An output schema exists, so return values need not be restated, and annotations cover the safety profile. The remaining gap is that the description never explains which parameters pair with which of the six enum shapes, which is the main source of misuse for an 8-parameter, shape-driven calculator.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so every parameter is documented in the schema itself, giving a baseline of 3. The description adds no mapping of which parameters each shape requires (e.g. radius for circle, semi_major/semi_minor for ellipse), so it does not go beyond the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('Calculate perimeter/circumference for common shapes'), which is enough to separate it from calculate_area and calculate_volume. It does not, however, explicitly name those siblings as the alternatives, so the differentiation is inferred rather than stated.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

There is no when-to-use guidance and no mention of alternatives in the overwhelmingly large math/measure sibling set (calculate_area, calculate_volume, calculate_regular_polygon, calculate_ellipse). The pointer to list_bundles is a discovery aid, not usage guidance for choosing this tool.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.